Tea, a product made from the leaves and buds of a plant, such as Camellia sinensis, is a popular beverage worldwide and a major source of dietary flavonoids. Tea also confers health benefits to humans such as lowering cholesterol and enhancing insulin activity. In addition, tea is considered an antioxidant, antimicrobial, as well as antiviral material and also possesses immunomodulatory and anti-carcinogenic properties. Accordingly, tea is considered a functional food beverage and therapeutic aid in many diseases. Polyphenols, particularly flavonoids, which comprise approximately 30% of the dry weight of the leaves, are among the major active components responsible for the beneficial properties of tea. Epigallocatechin gallate (EGCG) is the predominant flavonoid (flavan-3-ol or catechin) present in green tea polyphenols at a level of about 60%, while epicatechin (EC), epicatechin gallate (ECG) and epigallocatechin (EGC) are also present.